exten => _9[2-9].,1,ChanIsAvail(${TRUNK})
exten => _9[2-9].,2,Dial(${TRUNK}/423${EXTEN:1},60,r)
exten => _9[2-9].,3,HangUp
exten => _9[2-9].,102,Playback(tt-allbusy)
exten => _9[2-9].,103,Hangup